1. Field of the Invention
This invention relates to a driving force transmission mechanism for use in a camera and, more particularly, to a driving force transmission mechanism capable of transmitting a driving force by selecting driven systems provided in a camera.
2. Related Art Statement
Various driving force transmission mechanisms have been proposed which are arranged to selectively drive one of a plurality of driven systems in a camera by using one motor.
For example, Japanese Patent Laid-Open Publication No. 287547/1989 discloses a drive controller for a camera in which driving for shutter release, shutter change or changing operating ranges of a driving force transmission means is performed by rotating one motor in one direction, while driving for winding or rewinding a film is performed by rotating the motor in the other direction. In this controller, a torque of the motor is selectively transmitted to each of driven systems through a clutch mechanism.
The applicant of the present invention has also proposed a driving force transmission mechanism which is disclosed in Japanese Patent Laid-Open Publication No. 321986/1993. This mechanism is arranged to drive each of plural driven systems with one motor provided as a drive source in such a manner that one of driven gears for driving the plural drive mechanisms to be engaged with the motor is selected by the rotation of the motor in one direction through a planetary gear mechanism, and a torque is transmitted to the selected driven gear by the rotation of the motor in the other direction. The motor used in each of the above-mentioned conventional drive mechanisms is an ordinary motor having an output shaft always rotated at a fixed axial position.
Recently, single motor arrangements in which an output shaft can be operated for both rotational driving and axial movement have been proposed.
For example, Japanese Patent Laid-Open Publication No. 359657/1992 discloses a motor which has, as shown in a longitudinal sectional view of FIG. 9 of the present invention, a stator having plural stator coils 101, 102, and 103 arranged in an axial direction in a motor body 100, an output shaft 104 rotatable and axially movable, and a rotor 105 formed integrally with this shaft. For motor driving, at least one of the plurality of coils 101, 102, and 103 is energized. By changing the energized coil, the rotor 105 is caused to rotate and move along the axial direction. The output shaft 104 can be moved to set its leading end at each of positions 104A, 104B, and 104C, as shown in FIG. 9.
Japanese Patent Laid-Open Publication No. 130763/1993 also discloses a motor having a structure of the same type. This type of motor capable of performing rotational driving and axial driving of the output shaft will hereinafter be referred to as "an output shaft position changeable motor".
The camera drive controller disclosed in Japanese Patent Laid-Open Publication No. 287547/1989 uses an ordinary type motor as mentioned above and requires a clutch having a complicated construction because a torque of a pinion at a fixed axial position is transmitted by changing a transmission route to a plurality of driven gear. This drive controller therefore occupies a large space in the camera and requires a large number of component parts.
The driving force transmission mechanism disclosed in Japanese Patent Laid-Open Publication No. 321986/1993 also uses an ordinary type motor as in the above-mentioned drive controller and requires a changeover planetary gear mechanism although its does not require a complicated clutch mechanism. Accordingly, this driving force transmission mechanism also occupies a large space and requires a large number of component parts.
In each of the above-described controllers and mechanisms, the drive system changeover mechanism cannot be simply constructed since an output shaft position changeable motor such as that mentioned above is not used.